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On the Symmetry Constraints of CP Violations in QCD

Chuan-Tsung Chan
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Abstract

Three symmetry constraints on the CP violations in QCD are discussed in this paper. In order to generate CP violating observables from QCD, these constraints require: (1) spontaneous chiral symmetry breaking, (2) explicit chiral symmetry breaking, e.g., finite quark masses, (3) $U_A(1)$ anomaly, in addition to a nonzero $\thetabar$ parameter. A pictorial illustration is used to unify and elucidate these constraints and indicate a dual relation between quark mass and the quark condensate. Based on the symmetry constraints, a dynamical suppression scenario to solve the strong CP problem within QCD is examined. We conclude that a solution of the strong CP problem has to involve physics beyond the standard model.

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Chuan-Tsung Chan. 1997-04-28. On the Symmetry Constraints of CP Violations in QCD. https://arxiv.org/abs/hep-ph/9704427

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